Complete hypersurfaces with constant mean curvature in a unit sphere

By investigating hypersurfaces M(n) in the unit sphere S(n+1) (1) with constant mean curvature and with two distinct principal curvatures, we give a characterization of the torus S(1)(a) x S(n-1)(root 1 - a(2)) where a(2) = 2+nH(2) +/- root n(2)H(4)+(n-1)H(2)/2n(1+H(2)). We extend recent results of Hasanis et al. [5] and Otsuki [10].